What happens if I hook up a second PSU just to power a video card?

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JCDenton

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Jan 6, 2008
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I'm worried my Antec truepower 850w won't be able to hang with SLI GTX280, yet I have another 550watt psu sitting around just collecting dust. What would happen if I just plugged in the PCIE cables from that second PSU to the second GTX280? Would it work?
 
You can but you will need an adapter that will connect both of the 24 pin power connectors so that when you turn your computer on it will also turn on both psu.
 
You can but you will need an adapter that will connect both of the 24 pin power connectors so that when you turn your computer on it will also turn on both psu.
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Thanks, good to know. Kind of makes the thing more of a frankenstein system than it would have been already though.

they have psus for 5.25" bays for just this
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prices? links? i've never seen anything like this.
 
A downside to this is you can end up with extra power overhead running 2 PSU's.
As long as you can remain near the most efficient power consumption levels for each PSU, the impact is minimised
This assumes that both PSU's have near equivalent efficiency ratings.

It will work fine though, I have run multiple PSUs many times.
Do try and get the adapter to power them both on/off at the same time.
You can kill hardware if one PSU is down while the other is up and current tries to leak through components to parts of the circuit that are normally powered.
The design of PC parts may not be resistant to this kind of abuse.
 
Nenu said:
You can kill hardware if one PSU is down while the other is up and current tries to leak through components to parts of the circuit that are normally powered.
The design of PC parts may not be resistant to this kind of abuse.
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Thanks for this info. I don't think I'm going to fuck around when my potential graphics cards are this expensive....looks like I'll just have to sell my PSU and buy a new one. At least I only paid like $100, so there won't be much loss on it.
 
JCDenton said:
Thanks for this info. I don't think I'm going to fuck around when my potential graphics cards are this expensive....looks like I'll just have to sell my PSU and buy a new one. At least I only paid like $100, so there won't be much loss on it.
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I stated that as a caution, it wasnt meant to put you off :)
Damage takes time to occur so as long as the switchover is fairly fast, before anything gets a chance to heat up, it should be fine.
Some components will be protected from this type of power problem but some may not be.
Just a cautious note.
 
I am not sure about your particular power supply but 850watts is more then enough to run two 280s. in fact johnnyguru has 3 of then on a 800watt with a little room to spare (pulling 740 watts from the wall, I am guessing around 600 watts for the actual system). you can look here

http://www.jonnyguru.com/forums/showthread.php?t=4447

I think everyone is going power crazy here.

Also, there is no problem running two PSU, it is done all the time.
 
The Quattro power supplies have way more than enough power to run a pair of those cards.
 
Nenu said:
You can kill hardware if one PSU is down while the other is up and current tries to leak through components to parts of the circuit that are normally powered. The design of PC parts may not be resistant to this kind of abuse.
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FYI: It isn't 1998 anymore. Unless you hook up two molex connectors from each power supply together, you won't have any problems...even then, you're going to trip the fuse in the power supply.
 
yea you can but try to add it to the exterior cause it will get pretty hot in the case
 
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